1. Field of the Invention
This invention relates to an ink ribbon for thermal transfer printing, and more particularly to an ink ribbon to be used for producing a dry transfer material which is capable of transferring an ink image onto a surface of a receiving material that has a poor wetting property and high releasability. The ink ribbon is used with a thermally transfer printing type printer, typewriter or word processor. The ink that is transferred to a transfer sheet is capable of transfer printing effectively onto a receiving material upon application of pressure to a back surface of the transfer sheet.
2. Description of Related Art
Recently, a device for producing a dry transfer material which comprises a transfer sheet for dry transfer material and a ribbon cartridge in which an ink ribbon for producing the dry transfer material is stored has been developed and used widely. As such a device, Tape Printer "P-touch", manufactured by Brother industries, Ltd., is well known. A thermal head is installed in the device for producing the dry transfer material. The ink ribbon for producing the dry transfer material is brought into contact with a transfer sheet by the thermal head and a number of heating elements aligned on the thermal head are caused to generate heat according to electrical signals, whereby the ink on the ribbon in contact with the heating elements is heated through a base sheet of the ribbon and fused onto the transfer sheet.
Further, as described in U.S. Pat. No. 4,870,427 (corresponding to Japanese Laid-Open Patent Publication No. 63-128990, Japanese Laid-Open Patent Publication No. 63-128991, etc.), the ink ribbon for producing the dry transfer material comprises an ink layer which is arranged on a film-like ribbon substrate and contains a resin having a pressure-sensitive adhesive property, with a coloring matter therein, and a control layer which is arranged on the ink layer and contains a resin having a thermo-sensitive adhesive property.
Another ink ribbon for producing dry transfer material comprises, as described in Japanese Laid-Open Patent Publication No. 63-251287, a layer arranged on a film-like ribbon substrate and contains a resin having a pressure-sensitive adhesive property and an ink layer which is arranged on the resin layer. The ink layer contains a resin having a thermal-sensitive adhesive property and a coloring matter.
The user installs a ribbon cartridge, in which an ink ribbon for producing dry transfer material is stored, in the device for producing the dry transfer material. The user then inputs the characters or figures, by means of a keyboard or other external data source, that the user wants recorded on the dry transfer material. Following the data input, only the heat-generating elements of the device corresponding to the characters or figures to be recorded are heated according to the input character and figure data. The ink of the ink ribbon for producing the dry transfer material is transferred to a transfer sheet, the transfer sheet formed by a transparent resin sheet, whereby the dry transfer material, that is the transferred images consisting of characters and figures are formed on the transfer sheet, is produced. To use the dry transfer material, the user presses the dry transfer material against a receiving material and transfers the ink image onto the surface of the receiving material.
However, there is a problem that the quality of the transferred image is not good as produced by transferring from the dry transfer material to the receiving material.
To transfer the known dry transfer material, the user must place the side of the transfer sheet having the ink transfer image in contact with the receiving material such as paper, plastic, metal, and wood, and then the user must rub the back side of the transfer sheet for a long period of time.
However, it is difficult to obtain a high quality transferred image because the collapse and spreading of the ink transferred image that results if the transfer sheet is insufficiently fixed with respect to the receiving material surface and the transfer sheet shifts position during the rubbing and transfer.
The inventors of the invention studied the problem and found the reason why the user had to keep rubbing the transfer sheet for such a long period of time, was because the pressure-sensitive adhesive property of the resin, such as described in EXAMPLE 2, column 18 of U.S. Pat. No. 4,870,427, was weak.